To properly direct the forward beam, headlamps need to be adjusted. With headlamps, and the available space under the vehicle hood becoming smaller, the adjustment mechanism needs to become both more accurate and less bulky, and the associated access space needs to be minimized. Existing headlamp adjustments include a variety of shaft and gear linkages. By turning an end of the linkage, a threading advances or retracts a reference point of the headlamp module. The headlamp module then pivots, thereby redirecting the forward beam. An advantage to the shaft and gear type linkage is that direct access to the back of the headlamp is no longer necessary. The rear facing linkage can be brought up ninety degrees, so the linkage ends near the top rear of the headlamp. The adjustment can then be made from the top of the headlamp. Nonetheless, vehicle manufacturers would prefer to eliminate the shaft and gear linkages, as they still take up space. There is then a need for an adjustment linkage for vehicle headlamp that minimizes the associated access volume.
There are a number of other problems with the shaft and gear type linkage. Primarily, there are too many components, which means the materials, and assembly costs are high, and there are more elements that may be defective, or fail. There is then a need to reduce the number of elements in the adjustment linkage. Hands, tools or parts tend to rest on or hit the top end of the linkage. The hand, tool, part or linkage may then be damaged. There is then a need to remove the top exposed linkage.
Commonly, a headlamp module is mounted on a backplate that is bolted to the vehicle. The headlamp then pivots with respect to the backplate. The headlamp as a whole moves with respect to the vehicle, hereby upsetting water seals, and tight finish lines around the headlamp. To avoid these results, headlamps are now being made with a housing enclosing an adjustable internal reflector. The housing is bolted to the vehicle, while the reflector inside may be aimed independently of the housing. The adjustment linkage must then pass from the exterior through the housing to couple with the internal reflector. The same adjustment linkage problems as described before must still be overcome, but also, to lessen or prevent the likelihood of the housing interior from fogging up, a water seal must now be included in the length of the adjustment linkage. There is then a need for a simple, compact, water sealed adjustment linkage for use in vehicle headlamps.
A further problem is to be able to aim the headlamp after it has been dismounted. Currently, headlamps are being designed that include bubble type levels, and other types of leveling and marking items. The threaded adjusters usually require several turns of the threading to bring the headlamp module into proper fine tune, but two or three threadings of the adjustment linkage is only a small distance along the adjustment shaft, too small to be accurately judged by most humans. There is then a need for scaling the number of threadings to a convenient beam angle measurement for human detection. Since, the scaling mechanism must be initially set during factory assembly, and potentially reset during regular maintenance or repair, there must be zeroable feature to the scale.
Examples of the art shown in U.S. patents include:
U.S. Pat. No. 4,574,334 issued to Kenkichi Igura on Mar. 4, 1986 for a Device for Adjusting the Inclination of the Light Axis of Headlamps of a Motor Vehicle shows a pivoted headlamp assemble, with a threaded shaft driver. A hand knob is shown coupled to a gearing that threads the adjustment shaft in and out.
U.S. Pat. No. 4,674,018 issued to Francis E. Ryder et al on Jun. 16, 1987 for a Head Lamp Adjusting Mechanism shows a pivoted headlamp adjusted by a driven threaded shaft. A Right angle coupling is shown with a gear box coupling between two permanent shafts is shown.
U.S. Pat. No. 4,731,707 issued to David R. McMahan on Mar. 15, 1988 for a Vehicle Headlamp Assembly shows a pivoted headlamp adjusted by a driven threaded shaft. The drive mechanism includes two permanent shafts coupled at right angles by a gearbox type coupling.
U.S. Pat. No. 5,068,769 issued to Toru Umeda et al on Nov. 26, 1991 for a Horizontal Sighting Adjustment linkage for Head-Lamps shows a pivoted headlamp adjusted by a driven threaded shaft. The drive mechanism includes a thumb wheel that turns a gear coupled to the adjustment shaft.
U.S. Pat. No. 5,070,433 issued to Ulrich Zillgitt et al on Dec. 3, 1991 for a Headlight for a Motor Vehicle having an Adjustable Motor-Driven Reflector shows a geared motor drive for automatically adjusting the headlamp aiming.